218 lines
5.1 KiB
ArmAsm
218 lines
5.1 KiB
ArmAsm
/*
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* Ported to boot 386BSD by Julian Elischer (julian@tfs.com) Sept 1992
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*
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* Mach Operating System
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* Copyright (c) 1992, 1991 Carnegie Mellon University
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* All Rights Reserved.
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*
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* Permission to use, copy, modify and distribute this software and its
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* documentation is hereby granted, provided that both the copyright
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* notice and this permission notice appear in all copies of the
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* software, derivative works or modified versions, and any portions
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* thereof, and that both notices appear in supporting documentation.
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*
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* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
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* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
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* ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
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*
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* Carnegie Mellon requests users of this software to return to
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*
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* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
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* School of Computer Science
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* Carnegie Mellon University
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* Pittsburgh PA 15213-3890
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*
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* any improvements or extensions that they make and grant Carnegie Mellon
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* the rights to redistribute these changes.
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*/
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/*
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* HISTORY
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* $Log: boot2.S,v $
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* Revision 1.3 1993/07/13 21:51:36 mycroft
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* Fix addressing bug in bdb junk.
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*
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Revision 1.2 1993/07/11 12:02:22 andrew
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Fixes from bde, including support for loading @ any MB boundary (e.g. a
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kernel linked for 0xfe100000 will load at the 1MB mark) and read-ahead
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buffering to speed booting from floppies. Also works with aha174x
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controllers in enhanced mode.
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*
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* 93/07/06 bde
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* Delete LOADMSG define (not used).
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*
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* 93/06/29 bde
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* Use EXT.
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*
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* Initialize GDT and IDT pointers at boot time.
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*
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* Convert (drive | head | junk) to drive arg for boot() (not strictly
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* necessary - boot() only uses drive & 0x80).
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*
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* 93/06/28 bde
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* Initialize top bits of %eax for setting _ouraddr. start.s
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* initialized them suitably, but this isn't documented, and the BIOS
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* isn't documented to preserve them.
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*
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* Use addr32 for setting _ouraddr. Without this, there were extra bytes
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* 0, 0 after the store. These decode as "add %al, (%bx,%si)" in 16-bit
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* mode would clobber something (except %al is very likely to be 0 :-).
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*
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* Clear the bss. This may be unnecessary. Some is already cleared in
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* the disk image.
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*
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* Loop if boot() returns.
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*
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Revision 1.1 1993/03/21 18:08:33 cgd
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after 0.2.2 "stable" patches applied
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* Revision 2.2 92/04/04 11:35:26 rpd
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* From 2.5
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* [92/03/30 rvb]
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*
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* Revision 2.2 91/04/02 14:39:21 mbj
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* Put into rcs tree
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* [90/02/09 rvb]
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*
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*/
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#include "asm.h"
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/* Conventional GDT indexes. */
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#define BOOT_CS_INDEX 3
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#define BOOT_CS16_INDEX 5
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#define BOOT_DS_INDEX 4
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#define DB_CS_INDEX 14
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#define DB_CS16_INDEX 15
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#define DB_DS_INDEX 16
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#define GDT_INDEX 17
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/* Vector numbers. */
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#define BREAKPOINT_VECTOR 3
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#define DEBUG_VECTOR 1
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/*
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* boot2() -- second stage boot
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*/
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.globl EXT(ouraddr)
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ENTRY(boot2)
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data32
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subl %eax, %eax
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mov %cs, %ax
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mov %ax, %ds
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mov %ax, %es
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data32
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shll $4, %eax
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addr32
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data32
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movl %eax, EXT(ouraddr)
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/* fix up GDT entries for bootstrap */
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#define FIXUP(gdt_index) \
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addr32; \
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movl %eax, EXT(Gdt)+(8*gdt_index)+2; /* actually movw %ax */ \
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addr32; \
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movb %bl, EXT(Gdt)+(8*gdt_index)+4
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data32
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shld $16, %eax, %ebx
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FIXUP(BOOT_CS_INDEX)
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FIXUP(BOOT_CS16_INDEX)
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FIXUP(BOOT_DS_INDEX)
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/* fix up GDT entry for GDT, and GDT and IDT pointers */
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data32
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movl %eax, %ecx
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data32
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addl $ EXT(Gdt), %eax
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data32
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shld $16, %eax, %ebx
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FIXUP(GDT_INDEX)
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addr32
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data32
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movl %eax, EXT(Gdtr)+2
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data32
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addl $ EXT(Idt), %ecx
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addr32
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data32
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movl %ecx, EXT(Idtr_prot)+2
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/* %es = vector table segment for a while */
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push %es
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data32
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subl %eax, %eax
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mov %ax, %es
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/* fix up GDT entries for bdb */
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data32
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movl $4*DEBUG_VECTOR, %esi
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addr32
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movl %es: 2(%esi), %eax /* actually movw to %ax */
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data32
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shll $4, %eax
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data32
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shld $16, %eax, %ebx
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FIXUP(DB_CS_INDEX)
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FIXUP(DB_CS16_INDEX)
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FIXUP(DB_DS_INDEX)
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/* Fetch entry points of bdb's protected mode trap handlers. These
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* are stored at 2 before the corresponding entry points for real mode.
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*/
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data32
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subl %ebx, %ebx
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addr32
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movl %es: (%esi), %ebx /* actually movw to %bx */
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data32
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subl %ecx, %ecx
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addr32
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movl %es: 4*(BREAKPOINT_VECTOR-DEBUG_VECTOR)(%esi), %ecx
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/* actually movw to %cx */
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/* %es = bdb segment for a while */
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data32
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shrl $4, %eax
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mov %ax, %es
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/* fix up IDT entries for bdb */
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movl %es: -2(%ebx), %eax /* actually movw to %ax */
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addr32
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movl %eax, EXT(Idt)+8*DEBUG_VECTOR /* actually movw %ax */
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movl %es: -2(%ecx), %eax /* actually movw to %ax */
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addr32
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movl %eax, EXT(Idt)+8*BREAKPOINT_VECTOR /* actually movw %ax */
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/* finished with groping in real mode segments */
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pop %es
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/* change to protected mode */
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data32
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call EXT(real_to_prot)
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/* clear the bss */
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movl $ EXT(edata), %edi /* no EXT(_edata) - krufty ld */
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movl $ EXT(end), %ecx /* or EXT(_end) */
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subl %edi, %ecx
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subb %al, %al
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rep
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stosb
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movzbl %dl, %edx /* discard head (%dh) and random high bits */
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pushl %edx
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call EXT(boot)
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oops:
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hlt
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jmp oops
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.data
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.align 2
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#if 0 /* XXX this would give losing "_ouraddr :". Better declared in C */
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EXT(ouraddr):
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#else
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_ouraddr:
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#endif
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.long 0
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